How Marijuana Might Help Aging Brains

Marijuana isn’t exactly synonymous with mental sharpness, but surprising new research has found that it might help protect the brain from the effects of aging.

A German study on mice published in the journal Nature Medicine found that low, regular doses of tetrahydrocannabinol (THC), the psychoactive ingredient found in marijuana, may help to keep our brains from slowing down as we get older. For the study, researchers from the University of Bonn and Hebrew University spent a month giving daily THC to mice that were two months, one year, and 18 months old, and studied the effects on each.

Scientists first tested the mice on their ability to recognize familiar objects and navigate a water maze without the influence of THC and found that, while younger mice did well, older mice struggled. Once they were given THC, the younger mice had a drop in performance, but older mice showed improvement that lasted for weeks afterward — and even did as well as younger mice that had no THC.

Researchers say that THC in older mice might stimulate the brain’s endocannabinoid system, a group of brain and nervous system receptors that become less active as we age.

Of course, the study was conducted on mice, not humans, and it’s too soon to recommend that adults start taking daily doses of THC based on this. But The Guardian reports that the scientists are planning to start a clinical trial to test this on humans later this year. “If we can rejuvenate the brain so that everybody gets five to 10 more years without needing extra care, then that is more than we could have imagined,” study co-author Andras Bilkei-Gorzo told The Guardian.

Norbert E. Kaminski, PhD, director of the Institute for Integrative Toxicology at Michigan State University, tells Yahoo Beauty that while it’s too soon to draw any conclusions from the research, there may be something to it. “If low doses of THC decrease decline in cognitive function in senior citizens, this could be beneficial,” he says.

Kaminski also notes that many diseases that cause a decline of cognitive function, such as Alzheimer’s disease and Parkinson’s disease, are thought to be due, in part, to chronic inflammation in the brain. Cannabinoids like THC have anti-inflammatory properties, he says, which may be beneficial for some older patients suffering from certain neurodegenerative diseases.

Gary Wenk, PhD, a professor in the departments of Psychology & Neuroscience & Molecular Virology, Immunology, and Medical Genetics at the Ohio State University and Medical Center who is a member of the Governor’s Marijuana Advisory Committee, agrees. He tells Yahoo Beauty that the research “presents clear evidence for the cognitive and neurological benefits of low-dose marijuana use in the aging brain.” Wenk, who also has studied the impact of low-dose cannabinoids, says THC acts by reducing brain inflammation and its consequences upon normal brain function as people age. “It’s a very positive effect that is seen at quite low doses,” he says.

Seth Ammerman, MD, a clinical professor at Stanford University’s department of pediatrics in the division of adolescent medicine, tells Yahoo Beauty that THC affects younger brains differently because it can disrupt normal pathways of brain development. But once a person’s brain has fully developed, Ammerman says, it’s “possible” that THC can help stabilize elements in the endocannabinoid system so that the effects of aging on the brain are tempered in a way.

Of course, THC is responsible for the high that people feel from marijuana, so dosing is important. Women’s health expert Jennifer Wider, MD, tells Yahoo Beauty she has some concerns.

“It has been well-established that THC comes along with side effects — even in older people,” she says, listing anxiety, paranoid thinking patterns, drowsiness, slowed sense of time, and dizziness as examples. “More research will be needed before this could become an accepted therapeutic modality.” Ammerman agrees, noting that “there are still a lot of unanswered questions.”